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This paper is the first part of a systematic study of the influence of W and Ir loading on the activity of Ir/WO 3 /ZrO 2 –SiO 2 catalysts for the ring-opening reaction of naphthenic molecules using methylcyclohexane (MCH) as a model compound. A series of Si-stabilized tungstated zirconias, WO x /ZrO 2 –SiO 2 , containing up to 3.5 at W/nm 2 was prepared. Ir-based catalysts containing up to 1.2 wt% were obtained by impregnation of these solids. The acidity of Si-stabilized tungstated zirconias, ZSiW x , was monitored by low-temperature CO adsorption followed by infrared (IR) spectroscopy. The results indicated the development of strong and relatively strong Bronsted acidity with increasing W surface density above a threshold of 1 atom W/nm 2 . The study of the Ir-doped solids showed that the texture, structure, and acidity of the ZSiW x solids were not affected by Ir deposition. The characterization of the metallic function was performed by hydrogenation of toluene and by CO adsorption at ambient temperature, followed by IR spectroscopy. Both methods indicated a low and constant Ir dispersion for the y Ir/ZSiW0 ( y = 0.3 , 0.6, 1.2) series. For a given Ir loading (1.2Ir/ZSiW x ), a progressive decrease in the dispersion of Ir metal with increasing W surface density was observed.

Electrospray ionization (ESI) time-of-flight mass spectrometry has been used to investigate the pH-dependence of phosphomolybdates in solution from pH = 1.7 to 10.2. Mass spectra are reported for the first time for H2Na2P2Mo5O232–, PMo9O313–, PMo10O343–, and PMo11O373–. The pH dependence of phosphomolybdate species as measured by electrospray is compared with measurements reported for combined potentiometry—31P NMR. The pH ranges of most species are similar (±1 pH unit) when measured by these two methods, although some differences are observed. Protonation and solvation of phosphomolybdate species measured by ESI differ from those observed by 31P NMR. However, the core phosphomolybdate species are measured correctly by ESI.

Synthetic nylon-6 single molecular mass oligomers were studied by matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrometry. These oligomers, considered as model compounds for the study of nylon-6 polymers, gave good mass spectrometric results using both MALDI and ESI. In spite of the gentle nature of both techniques, the MALDI and ESI spectra showed evidence of end-group cleavage from the oligomer chains. MALDI-MS was found to give similar fragmentation patterns for all of the oligomer samples. An increase in doubly charged ion signals with increasing oligomer mass was observed in the ESI mass spectra, as was end-group fragmentation. Signals from oligomer clusters were observed in ESI-MS for the dimer, tetramer and hexamer, most likely due to non-covalent bonding among the low-mass oligomer molecules.

Electrospray ionization mass spectrometry (ESI-MS) was applied for the characterization of inorganic polyphosphates [orthophosphate, pyrophosphate, tripolyphosphate, trimetaphosphate, and tetrapolyphosphatel. The high selectivity of ESI-MS allows the detection of different polyphosphate species without preseparation by ion chromatography or capillary electrophoresis. Furthermore, ESI-MS does not require the incorporation of UV-absorbing chromophores into the analytical method for the detection of phosphates, unlike conventional UV-chromatographic methods. Limits of detection by ESI-MS were estimated to range from approximately 1 to 10 ng/mL. The quantification of polyphosphate samples as single-component and multicomponent mixtures was investigated. Linear signal response for single-component samples ranged from the limit of detection to approximately 10 microg/mL Quantification of polyphosphate in streamwater is demonstrated using the standard addition method. The effect of multi-polyphosphate components and salts on signal response was also studied. For concentrations less than 2.0 microg/mL, signal response from a tetrapolyphosphate sample was comparable to those obtained from tetrapolyphosphate-tripolyphosphate mixtures. Signal response obtained from tetrapolyphosphate in the presence of tripolyphosphate or NH4NO3 at higher concentrations (approximately 50 microg/mL and 35 microg/mL, respectively) was significantly lower relative to single-component standards (approximately 40%-70%).

The enhancement of the (M + H) + static secondary ion mass spectrometry (static SIMS) signal intensity resulting from pretreatment of silver sample substrates with aqueous halide acids was studied. Surface coverage experiments with silver halide surfaces prepared by aqueous halide acid treatment and electrodeposition indicated that the presence of silver halides alone could not account for the observed enhancement. Deuterium exchange studies showed that protons are adsorbed on the substrate during the acid treatment. It is likely that these protons are responsible for the improvement of static SIMS signal intensity by promoting the formation of (M + H) + species.

A series of WO 3 /ZrO 2 catalysts with tungsten (W) loadings varying from 0.5 to 11A wt.% WO 3 was prepared by incipient wetness impregnation. The surface coverage of these catalysts was monitored by ion scattering spectroscopy (ISS) and low-temperature CO adsorption. Comparable values for the surface coverage were obtained from ISS and CO adsorption. The surface coverage as determined by these two independent techniques increased from zero to 51 ± 3% as the W loading increased from zero to 4.5 wt% WO 3 , and leveled off at ∼54 ± 3% with further increases in W loadings. For catalysts with W loadings

A series of Mo/TiO 2 catalysts was prepared by equilibrium adsorption from aqueous solutions of (NH 4 ) 6 Mo 7 O 24 by varying the pH of the solution from 9.8 to 4. The Mo loading increases from 0.8 to 3.6 wt.% as the pH of preparation decreases. The surface coverage of the calcined catalysts was monitored by CO 2 chemisorption and ion scattering spectroscopy (ISS) measurements. Carbon dioxide uptake was determined in a standard BET system from the adsorption isotherms by extrapolating to zero pressure. Coverage measurements from ISS were obtained by monitoring the changes of the ISS Ti signal with Mo addition. Additional information about the dispersion of the Mo phase of these catalysts was obtained from x-ray photoelectron spectroscopy (XPS) measurements The XPS results evidenced the presence of a highly dispersed Mo phase. Carbon dioxide chemisorption results for Mo/TiO 2 catalysts indicated that the Mo coverage increases linearly from 0.16 to 0.93 with increasing Mo loading from 0.6 to 3.6 wt.%. These results were consistent with those determined by ISS measurements and are in good agreement with the predicted values for monolayer dispersion. These findings are in contrast with those obtained for alumina-supported catalysts, where the CO 2 chemisorption method has been show to overestimate the surface coverage. The origin of the apparent suitability of the CO 2 chemisorption method for monitoring the surface coverage of TiO 2 -based systems is discussed.

The selection of an appropriate internal standard (IS) for quantification by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is critical for the successful application of quantitative MALDI. Selection of the IS depends on the chemical similarity of the analyte and IS and the mass separation of the analyte and IS as a function of instrumental peak resolution. For the quantification of bovine insulin, a series of internal standards including horse heart cytochrome C, bovine insulin chain B, des-pentapeptide human insulin, and des-octapeptide porcine insulin was investigated. Des-pentapeptide human insulin was found to be the most appropriate internal standard (relative standard deviation of the standard curve slope = 2.99%, correlation coefficient = 0.988 in the range of 0.5-0.4 μmol/L). Two methods for measuring of the MALDI signal intensity were evaluated, direct peak integration following subtraction of a linear background and non-linear least squares curve fitting. The results obtained with these methods were equivalent.

Absolute surface coverages (θ) of a series of tungsten-alumina catalysts prepared by the equilibrium adsorption method were determined by ion scattering spectroscopy (ISS) and low-temperature CO adsorption. The θCO values for the W catalysts were very similar to those obtained with the ISS method, for a given W loading. A linear increase in W coverage with increasing W loading, reaching ~55% coverage for the 13.1% W solid, was observed. The calculated W cross-sections (22.0- 24.5A2/W) were in agreement with other reports in the literature. Due to the inherent limitations of each method, the combined use of ISS and low-temperature CO adsorption is recommended for estimating absolute surface coverages in tungsten-alumina catalysts.

The structure of Ti/Al2O3 supports (0–14 wt% Ti) and Co/Ti/Al2O3 catalysts (3 wt% Co) was examined by EXAFS. The results indicated that the Ti was present primarily as a highly dispersed surface phase. The Ti EXAFS results indicated that the Ti species were octahedrally coordinated. Evidence of Ti—Ti interactions was found for all loadings (2–14 wt% Ti) suggesting that the Ti surface species are present as small clusters of TiO2. The Co EXAFS results showed evidence for several structurally different Co surface phases as a function of Ti loading. Evidence of a Co species interacting with the Ti surface phase was observed for the 3% Co/2% Ti-3%Co/6%Ti catalysts. At the highest loadings studied, 3%Co/8%Ti and 3%Co/14%Ti, evidence was found for a CoTiO3-like phase.

The surface coverage of a series of rhenium-alumina catalysts prepared by equilibrium adsorption was determined by ion scattering spectroscopy (ISS) and infrared spectroscopy (IR). The coverage results were compared with those determined from previously published CO 2 chemisorption data. The ISS results show an almost linear increase in Re coverage with increasing Re loading, reaching ∼30% coverage for a loading of ∼6.5 wt.% Re. The near-linearity of the coverage with increasing Re content indicates a uniform build-up of the surface species. The Re cross-sections calculated from the corresponding surface coverages (24.8-30.5 A 2 /Re) were comparable with those previously reported for the Re/Al 2 O 3 system. The surface coverage determined from IR was shown to depend on the extent of dehydroxylation of the samples. Following pretreatment at 500°C, the coverage values for high loading catalysts were comparable with those obtained from ISS. However, the IR method yielded increasingly higher coverage values with decreasing Re loading. The Re cross-section values estimated from the corresponding surface coverages indicate an increased overestimation of the coverage with decreasing loading. As expected, the CO 2 chemisorption method consistently leads to an overestimation of the Re surface coverage.

The redox chemistry and the changes that occurred within the solids were studied for an excessively exchanged and a nearly stoichiometric CoZSM-5 zeolite as a function of pretreatment, reduction, and reoxidation conditions. Both gravimetric and volumetric techniques were used to determine this chemistry and the stoichiometry of the processes, which became reversible after the first couple of oxidation/reduction cycles. The catalyst was examined in its several states by diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscoy (XPS), and both the Faraday and Gouy magnetic susceptibility methods. With the excessively exchanged sample, it was found that Co3O4 formed after pretreatment with O2 and that Co metal was produced on reduction with either CO or H2 at 773 K in amounts corresponding to only a portion of the Co2+ originally present. The stoichiometric sample showed evidence for the presence of Co3+, but crystalline Co3O4 was not detectable. However, two different ...

X-ray photoelectron spectroscopy (XPS, ESCA) was used to determine the tungsten oxidation states in a 5 wt.% WO 3 /TiO 2 catalyst reduced in hydrogen in the temperature range 400-700 o C. Because, in the region of interest, W 4f overlaps with the Ti 3p energy level, a multiple analysis procedure including deconvolution, non-linear least-squares curve fitting and factor analysis was used to analyze the data. Deconvolution was better able to resolve the peaks in the W 4f region and thus elucidate the positions of the tungsten components for each reduction temperature. It was shown that there is a maximum of three W 4f doublets. The W 4f 7/2 peaks of these components were located at 35.5, 33.3 and 31.1 eV and they were assigned to W +6 , W +4 and W o , respectively. Factor analysis verified the presence of three spectral tungsten components X-ray diffraction verified the presence of W o on reduction at 675 o C. Non-linear least-squares curve fitting, using the positions from deconvolution, was able to determine the distribution of tungsten oxidation states as a function of reduction temperature: W +6 steadily decreased with increasing reduction temperature, W +4 initially appears at 408 o C and goes through a maximum around 580 o C; W o was first detected following reduction at 550 o C and was the only species present for reduction temperatures higher than 665 o C. From the distribution, it is proposed that, unlike the molybdenum systems, tungsten undergoes a more simplifed reduction process in which only one intermediate oxidation state (presumably W +4 ) is detected

A series of W/TiO 2 catalysts was prepared by incipient wetness impregnation with W loadings varying from 1.64 to 28.4 wt.% WO 3 . The coverage of the TiO 2 surface by W species was monitored by ion scattering spectroscopy (ISS). The results indicated that the W coverage increased from 21.6% for the 1.64 wt.% WO 3 /TiO 2 catalyst to ∼85% for catalysts with W loadings ≥10.3 wt.% WO 3 . These values agreed with those predicted from monolayer-like dispersion. The relatively constant coverage for W loadings >10.3 wt.% WO 3 was taken as an indication of multilayer or WO 3 formation. These results were consistent with Raman and x-ray photoelectron spectroscopy (XPS) data previously obtained in our laboratory

Quantitative FTIR studies of alumina hydroxyl groups have been used to measure the surface coverage of V/Al2O3 catalysts. The IR spectra show a preferential consumption of the most basic hydroxyls (3769 cm−1) with the initial V uptake. The integrated area of the hydroxyl region was used to calculate the surface coverage of the catalysts. The surface coverage increased to 0.63 as the V loading increased to 6.7 wt%. The surface coverage results obtained from IR were compared to those measured by ion scattering spectroscopy (ISS) and CO2 chemisorption. The surface coverages measured by ISS were comparable to those obtained by IR. In contrast, CO2 chemisorption appears to overestimate the surface coverage of the catalysts. The overestimation of the surface coverage by the CO2 chemisorption method is attributed to the preferential adsorption of the V phase onto the most basic hydroxyls, the same sites which interact with CO2.

Methodology for the quantitation of the distribution of oxidation states in reduced catalysts is reviewed. The adopted approach is based on the curve fitting the x-ray photoelectron spectroscopy (ESCA, XPS) envelope using a non-linear least squares curve fitting (NLLSCF) routine. The procedure was applied to the study of the reduction of Mo/TiO 2 and Mo/Al 2 O 3 catalysts. The distribution of Mo oxidation states obtained by ESCA was corrobrated by chemical measurements and correlated with catalytic activity. The limitations of the NLLSCF approach are discussed. It is shown that the uncertainties inherent in curve fitting methods can be minimized by the used of factor analysis. This data analysis technique provides an independent estimate of the number, positions, and shapes of components required to describe the Mo 3d envelopes in the reduced catalysts.

Principal component analysis (PCA) and target testing (TT) were performed on a series of reduced 2.5 wt.% Cr/Al2O3 catalysts to determine the number, positions, shapes and relative spectral compositions (i.e. Cr oxidation states) in Cr 2p spectra as monitored by ESCA. The results from PCA indicated the presence of only two abstract components. The abstract factors were transformed through iterative TT into real spectroscopic components that were attributed to Cr6+ and Cr3+. These factor analysis results were used in addition to non-linear least-squares curve fitting to provide a detailed description of changes in the Cr 2p envelope during reduction of the Cr/Al2O3 catalysts. Only two components were necessary to reproduce the original data.

Ion scattering spectroscopy (ISS) and x-ray photoelectron spectroscopy (XPS, ESCA) were used to study the dispersion of the vanadium phase and the coverage of Al2O3 by vanadium. A series of V/Al2O3 catalysts was prepared by equilibrium adsorption with vanadium loadings varying from 1.9 to 6.7 wt.% V. By monitoring the ISS Al/O intensity ratio the surface coverage of the catalysts was determined. The surface coverage increases from 15 to 33% with increasing the loading from 1.9 to 3.5 wt.% V. The results are consistent with a model of a uniform monolayer vanadium phase. For higher vanadium loadings the surface coverage appears to level off, suggesting the formation of a multilayer vanadium phase.

The distribution of supported species in a series of W/TiO2 catalysts (1.8 – 28 wt% WO3) has been determined by Raman and X-ray photoelectron spectroscopy (XPS, ESCA). The results show that three tungsten species are present on oxidic W/TiO2 catalysts. A tungsten interaction species is formed almost exclusively for catalysts with W loadings lower or equal to 6.7 wt% WO3. WO3 is observed above 6.7 wt% WO3. For W loadings higher than 10 wt%, a disordered W species WDS is also present. The amounts of WDS and WO3 increase with increasing W content above 10 wt% WO3.

This study shows that principal component analysis (PCA) in conjunction with iterative target transformation factor analysis (ITTFA) is able to provide an independent estimate of the number, position and, to a certain extent, the shape of spectral components required to describe the Mo 3d envelope as monitored by XPS in reduced Mo/TiO 2 catalysts. Three components were required to reproduce the original data. Abstract components from PCA were transformed through ITTFA into components which have spectroscopic meaning

35-2 FIELD Section Title:Chemistry of Synthetic High Polymers 45, 67 Laboratoire Catalyse et Spectrochimie, ENSICAEN, CNRS, Universite de Caen, Caen, Fr. FIELD URL: written in English; A series of WOx/TiO2 catalysts contg. between 0.6 and 3.4 W at./nm2 was prepd. by pore vol. impregnation using ammonium metatungstate soln. on crystd. TiO2. Characterization of the solids by X-ray diffraction and Raman and IR spectroscopy indicated that the W phase was present essentially as a surface W species. The results also suggested an increased degree of condensation of the W phase with increasing W surface d. The most condensed W species was characterized by a ?(W=O) vibration at 1017 cm-1. The IR or Raman bands attributed to sp. surface species of the solids were correlated with the abundance of relatively strong Bronsted acid sites and isopropanol dehydration activity. A direct correlation was obsd. between propene formation rate and the area of the band at 1017 cm-1, attributed to the most condensed W species. Furthermore, the abundance of this species appeared to be directly related to that of Bronsted acid sites capable of retaining lutidine following desorption at 573 K. The behavior of the WOx/TiO2 system was compared with that reported for the corresponding WOx/ZrO2 solids. Higher intrinsic activity (activity per W atom) was obsd. for WOx/TiO2 system. [on SciFinder(R)]

The local structure of oxidic Mo/TiO2 catalysts (0.5 to 13.5 wt.% Mo) has been studied using EXAFS and XANES. Both EXAFS and XANES results suggest that the Mo surface phase is octahedrally coordinated for all Mo loadings. The EXAFS results were also examined using principal component analysis (PCA) to determine the number of Mo species present on the Mo/TiO2 catalysts. Results from PCA of the Mo EXAFS spectra suggested the presence of three Mo species: two surface species and bulk MoO3.

The structure of a series of Fe/Al2O3 catalysts containing from 1 to 24 weight percent iron has been examined by XRD, EXAFS, Mössbauer, ESCA, and gravimetric analysis. Two iron phases, Fe2O3 and Fe+3 in solid solution in the alumina support, are characterized as a function of iron loading. The combination of ESCA H2 titration and gravimetric analysis allows both quantitative and qualitative measurement of the two species. The amount of Fe2O3 phase increases with increasing iron loading for Fe1 to Fe24, whereas the amount of Fe+3 solid-solution phase increases with increasing iron loading for Fe1 to Fe6 and then levels off to approximately 2.2 wt % Fe for Fe8 to Fe24. The particle size of the Fe2O3 phase, determined from ESCA measurements, increases with increasing iron loading.

EXAFS spectroscopy has been used to examine the effect of boron on the structure of Co/Al2O3catalysts. The EXAFS results from unmodified Co/Al2O3catalysts indicated that Co3O4was formed at Co loadings of 1.5 wt % Co and higher. The lowest-loading (0.7 wt % Co) catalyst showed evidence of both tetrahedral and octahedral Co surface species. Modification of the Co/Al2O3catalysts with 3 wt % B completely suppressed the formation of Co3O4for Co loadings of 6 wt % Co and lower. In the absence of Co3O4, the Co species formed on the 3 wt % boron-modified catalysts were in a highly disordered state with large first shell Co-O coordinations and large Co-O nearest-neighbor distances. Results from a constant Co loading series (3 wt % Co) indicated that Co3O4formation decreased as the boron loading increased. The distribution of supported Co species determined by EXAFS was compared with previous characterization by ESCA and gravimetric measurements; good agreement was found. A two-phase procedure was used to analyze the EXAFS data from the Co/B/Al2O3catalysts. This two-phase analysis considered both the fraction of Co EXAFS from bulk Co oxide (Co3O4) and the remaining fraction from Co surface species. This allowed the amount of Co3O4to be determined quantitatively and enabled structural information to be obtained from the Co surface phase.

Fe 2p is the preferred ESCA photoelectron peak to analyze iron species with an Al Kα anode, but it has proved difficult to use in quantitative measurements because of the large inelastic background generally associated with it. The Fe 3p photoelectron peak lends itself to a more accurate estimate of the iron intensity, but does not provide qualitative features sufficient to differentiate iron species

A series of Mo/Al 2 O 3 catalysts was prepared by using an equilibrium adsorption method. The dispersion of the molybdenum phase and coverage of the alumina surface by Mo species as a function of Mo loading were monitored by ion scattering spectroscopy (ISS) and X-ray photoelectron spectroscopy (XPS, ESCA). By modeling changes in the ISS Mo/Al intensity ratio as a function of molybdenum coverage, It is shown that, for Mo/Al 2 O 3 catalysts prepared by equilibrium adsorption, coverage of the alumina surface should be complete at a loading of 47×10 13 Mo atoms/cm 2 for calcined catalysts

X-ray photoelectron spectroscopy (ESCA or XPS), ion scattering spectroscopy (ISS), X-ray diffraction (XRD), H 2 chemisorption, and gravimetric analysis have been used to characterize a series of Ni/Th/SiO 2 catalysts. The information obtained from surface and bulk techniques has been compared with CO hydrogenation activity and selectivity of the supported nickel catalysts. Comparison of measured ESCA Th/Si intensity ratios with values predicted by a theoretical model shows that the particle size of the Th phase increases from 1.4 to 4.2 nm as the Th/Si atomic ratio increases from 0.0036 to 0.023. ESCA and XRD results also indicate that nickel is present as poorly dispersed NiO on the calcined unpromoted catalyst. Reducibility of the Ni phase in all catalysts exceeds 97%. ESCA data show that Th addition has little effect on Ni metal dispersion up to a Th/Si atomic ratio of 0.015. For higher Th loadings, the Ni dispersion increases from approximately 6 to 9% with increasing Th loading. H 2 chemisorption data suggest that Ni dispersion increases from 4.8 to 9.8% with increasing Th content. The turnover frequency (TOF) for CO hydrogenation calculated using ESCA estimates of Ni dispersion increases by a factor of 9 as the Th/Si atomic ratio increases from 0 to 0.015. For higher Th loadings the TOF decreases, but it remains seven times the value observed for the unpromoted catalyst. These results have been explained in terms of the Th surface coverage indicated by ISS. Th addition also increases olefin selectivity and the yield for higher hydrocarbons.

Ru methanation catalysts derived from oxidation of Ru{sub x}Th{sub y} intermetallics were characterized by X-ray photoelectron spectroscopy (ESCA), ion scattering spectroscopy (ISS), X-ray diffraction (XRD), BET surface area measurements, chemisorption, and gravimetric analysis. XRD measurements and gravimetric analysis indicated that all intermetallics were extensively decomposed by oxidation in air at 350{degree}C. ESCA and ISS Ru/Th intensity ratio measurements showed that surface segregation of ThO{sub 2} occurred for all catalysts. The structure of the intermetallic-derived (IM) catalysts can best be described as Ru particles embedded in a ThO{sub 2}-rich overlayer. Comparison of hydrogen and CO uptake with N{sub 2} BET surface area suggests that CO more accurately titrates surface Ru than does hydrogen. Extensive spillover of hydrogen from Ru to ThO{sub 2} was also observed for all IM catalysts. On the basis of CO chemisorption, the CO hydrogenation turnover frequency was comparable for all the IM catalysts.

Two series of silica supported cobalt catalysts were prepared by incipient wetness impregnation, one by varying the calcination temperature (200-400{degree}C, 3 wt % Co) and the other by changing the cobalt loading (1-10 wt % Co). Examination by ESCA, XRD, and H{sub 2} chemisorption showed that Co{sub 3}O{sub 4} is the dominant phase. The cobalt phase is reduced to cobalt metal at 400{degree}C. The cobalt particle sizes obtained from ESCA correlated well with those derived from H{sub 2} chemisorption and XRD line broadening. The turnover frequency of Co/SiO{sub 2} for CO hydrogenation was invariant with cobalt dispersion in the range of 6-20% dispersion.

The surface coverage of a series of rhenia–alumina catalysts prepared by equilibrium adsorption was determined by low‐temperature CO adsorption. The results show a linear increase in the coverage of the Re oxide on the alumina support up to 24% with increasing Re loading from 0 to ca. 5.6 wt%. This is consistent with a uniform build‐up of the surface species. The coverage values measured by this method agreed very well with those obtained by ion scattering spectroscopy.

A series of WO(3)/ZrO(2) catalysts with tungsten (W) loadings ranging from 0.5 to 11.4 wt% was prepared by incipient wetness impregnation on a preformed ZrO(2) support. The oxidic catalysts were characterized using XRD, Raman spectroscopy, XPS, ISS, and IR spectroscopy. XRD and Raman results showed that the ZrO(2) support was predominantly present in the monoclinic form. XPS and Raman measurements indicated the formation of increasing amounts of W interaction species for catalysts with W loadings up to 8.8 wt% WO(3). In addition to the W interaction species, bulk WO(3) was also observed for catalysts with W loadingsor = 3.0 wt% WO(3). Comparison of the XPS results with coverage measurements by ISS and CO adsorption suggests that the W surface phase is in the form of two-dimensional polymeric patches for catalysts with W loadings 3.0or = wt% WO(3)or = 4.5. For catalysts with W loadings4.5 wt% WO(3), the results indicated an additional build-up of a bilayer (or multilayer) polymeric W species. Analysis of the hydroxyl region of ZrO(2) by IR spectroscopy showed that initial additions of W occur on the high frequency hydroxyl group. A schematic for the structure of the catalysts has been proposed based on the above observations.

X-ray photoelectron spectroscopy (ESCA or XPS), laser Raman spectroscopy (LRS), and X-ray diffraction (XRD) have been used to characterize the dispersion and chemical state of a series of TiO 2 Al 2 O 3 carriers and a series of 3% Co Al 2 O 3  TiO 2 catalysts. It was found that titania is well dispersed on alumina for Ti loadings less than 14 wt%. The formation of a TiO2: Al2O3 surface phase occurred for carriers in the 1 to 6 wt% Ti range. Formation of anatase occurred, in addition to the TiO2:Al2O3 surface phase, at loadings in excess of 6 wt% Ti, with the amount of anatase increasing with increasing titania loading. ESCA data indicate that the dispersion of cobalt supported on the titania-modified alumina carriers increased with increasing titania loading. XRD and LRS results show that the increase in dispersion can, in part, be ascribed to the formation of a surface cobalt phase at the detriment of the Co3O4 phase.

The use of solid-state mass spectrometry for studying polymers is evaluated. Structural differences between polymers can be obtained by laser mass spectrometry by observing fingerprint-like spectra in the range m/z

The influence of boron on the chemical state and dispersion of Co Al 2 O 3 catalysts has been investigated by bulk and surface spectroscopic techniques. Three series of Co Al 2 O 3 catalysts were studied: one containing a constant Co loading of 3 wt% and boron loadings of 0.3 to 3 wt%, and two series containing 0.7 to 10 wt% Co and constant boron loadings of either 0 or 3 wt%. In the absence of boron, Co dispersion decreased with increasing Co loading above 1.5 wt% Co. The presence of boron had little effect on Co dispersion at low Co loadings, while catalysts with Co loadings in excess of 1.5 wt% exhibited an increase in Co dispersion compared to boron-free catalysts. X-ray photoelectron spectroscopy, diffuse reflectance spectroscopy, and gravimetric analysis were used to quantify the Co species present on the catalysts as a function of both Co and boron loading. In the absence of boron, Co exists as tetrahedral and octahedral Co2+ at low Co loadings, while Co3O4 is the primary phase at higher Co loadings. In the presence of boron, Co3O4 formation is suppressed for catalysts with Co loadings less than 8 wt% in favor of octahedral Co2+ and minor amounts of Co borate. The formation of Co3O4 occurs at Co loadings greater than 6 wt% for boron-containing catalysts. A mechanism is described to account for the effect of boron on the dispersion and chemical state of Co.

Two molybdenum species (i.e., Mo interaction species and MoO3) are identified and quantitated by Raman spectroscopy for a series of MoTiO22 catalysts. The Mo interaction species is shown to increase with Mo loading up to 6 wt% MoO3 and to level off at higher Mo loadings. MoO3 is detected at 7.5 wt% MoO3TiO2 and shown to increase linearly with further Mo additions. The molybdenum speciation determined from Raman data is shown to correlate with ESCA and X-ray diffraction measurements.

Two series of Ni x Si y (NiSi 2 , Ni 3 Si 2 , Ni 2 Si and Ni 5 Si 2 ) and Ni x Th y (Ni 3 Th 7 , Ni 2 Th, NiTh and Ni 5 Th) intermetallics have been prepared by melting the component metals in an induction furnace. Surface and bulk characterization were carried out by the combined use of several techniques: Ion Scattering Spectroscopy (ISS), X-ray Photoelectron Spectroscopy (XPS, ESCA) and X-ray diffraction (XRD). The results show that the surfaces of the untreated Ni x Si y and Ni x Th y alloys are all nickel-poor compared to the bulk. Oxidation treatment further decreases the surface Ni content of Ni x Si y alloys. Surface enrichment in nickel is, however observed in the case of Ni x Th y intermetallics upon oxidation. Oxidized Ni x Si y alloys which are reportedly active in methanation (Ni 5 Si 2 , Ni 2 Si) show a relative surface enrichment in nickel and evidences of partial decomposition whereas silicon-rich alloys are essentially stable. Oxidized Ni 5 Th, which exhibits the greater methanation activity within the Ni x Th y system, shows equally the highest surface concentration in nickel. The correlation between Ni surface content and CO conversion data will be discussed in terms of the relative configuration of the Ni phase with respect to ThO 2 .